Coronary CT-Derived Fractional Flow Reserve

Abstract

Coronary artery disease (CAD) is the leading cause of mortality in the United States and is accountable for a significant portion of overall healthcare costs. Non-invasive imaging plays a major role in the modern workup of CAD. This article will educate the reader on the foundations of computed tomography-derived fractional flow reserve (CT-FFR) and provide guidance for its appropriate clinical use. Coronary computed tomography angiography (CCTA) has high sensitivity and negative predictive value to non-invasively rule out CAD. However, discrimination of ischemia-inducing lesions based on macroscopic anatomy derived from either CCTA or the gold standard for the detection of anatomic stenoses, invasive coronary angiography, is suboptimal. Invasive pressure wire-guided estimation of FFR across coronary stenoses yields reliable functional information regarding the effect of a lesion on myocardial blood supply. Recently, non-invasive methods have attempted to calculate FFR from CCTA datasets. CT-FFR allows for higher specificity compared to CCTA alone, while preserving the high sensitivity and negative predictive value of CCTA. Whereas off-site solutions for CT-FFR calculation have been heavily validated and are clinically available, other techniques that can be performed on-site have recently evolved and are under current investigation. Non-invasive CT-FFR has facilitated the reliable assessment of the hemodynamic significance of coronary artery stenosis, potentially increasing the specificity of the modality while maintaining its excellent sensitivity.